I think that it does not work because you set it over an "empty" video spot.If you set a video in the video spot does it work ?Or if you set an transparent polygon spot, instead of an empty video spot, does it work ?

Well the YouTube video should stream in but, how did you add a YouTube to a Movie Polygon.. Did you download the entire movie and save the movie in one of your folders, since you cannot add a YouTube into Polygon..

... but if your video is sooo big, you might need to consider a player to stream the video in.. But... that cannot be added to a spot.. It can only go into a kolor box.. I have requested as a future feature that it the kolor box can be attached to the actual pano so it moves with the pano.. This would open up so many opportunities. But.. I do not think its possible ... but if it is, we will not see it for a very long time..